The present invention relates to a method for operating an internal combustion engine, as well as to a corresponding device.
The German Published Patent Application No. 199 12 770 describes a method and a corresponding device for operating an internal combustion engine, the setpoint value for the dwell period of a controllable switch of an ignition device being expressed as the number of clock pulses of a clock-pulse generator, the clock pulses being generated independently of the movement of the crankshaft. The ignition is triggered after reaching the calculated number of clock pulses.
Furthermore, the German Published Patent Application No. 199 06 390, describes a method and a corresponding device for operating an internal combustion engine, differentiation being made between two output modes. Firstly, in the ignition-angle output mode, the moment of ignition is output in such a manner that the calculated ignition angle is honored. Secondly, in the charging-time output mode, an ignition is triggered when a specific charging time of the ignition coil has elapsed.
In contrast, an example method of the present invention and a corresponding example device according to the invention may take into consideration, after calculating the setpoint values, the dynamics of the internal combustion engine as well. The internal combustion engine may operate closer to time happenings, and thus may avoid errors developing due to the dynamics. Moreover, it may be ensured that, for example, even if a trigger wheel sensor malfunctions, at least the events associated with the setpoint values already calculated are output in any case.
Further developments and improvements of the example method specified or of the example device may be permitted. The pulse counter may be initialized after each reference pulse, since an adaptation to a new dynamic of the internal combustion engine may thus occur in a simple manner. Moreover, event moments may be calculated in a cylinder-individual manner, since the cylinders may have different properties. Setpoint values may be independently calculated as a function of operating parameters and operating modes with the aid of a control unit separate from an output unit, since the computing capacity of the ECU (electronic control unit) may thereby be utilized. For an optimal realization of the ignition of an internal combustion engine, a moment at which the controllable switch is closed and a moment of ignition or a dwell-period duration may be calculated, or, in the case of a pulse pull-ignition, the number of sparks in a spark band, a recharge time or a break time may be used as setpoint values. To achieve a proper allocation of the processes in the internal combustion engine timewise, the setpoint values may be relayed in their time sequence to the output unit. Thus, long dwell periods may be recognized early and output reliably. The events to be controlled in the internal combustion engine may be configured as a function of operating parameters, since the state of the internal combustion engine may be imaged as precisely as possible. Moreover, various operating modes may be differentiated to represent different states of the internal combustion engine as accurately as possible. In a further example embodiment, the operating mode may be held constant over at least two segments, since undesirable transitions from one operating mode to the next may thereby be avoided. If the number of clock pulses that may pass by until a specific event is very small or negative, then the speed of the control may not be sufficient to trigger the event in time. Therefore, the calculated number of clock pulses may remain unaltered in this case. In order to be able to observe the dynamics of the internal combustion engine long in advance, or to be able to ensure long dwell periods, it may be required that the event moments for a specific number of cylinders be calculated in a cylinder-individual manner.
According to a further example refinement of the invention, provision may be made in the output unit for storage units whose contents are dependent on the triggering of the events. A success-bit storage location may be provided which has a first value when an event has ended, and has a second value when the event has been calculated once more in a new cycle. The successful completion of the process of the internal combustion engine may be monitored, and false triggerings may be forestalled as long as no new value has yet been calculated for a new cycle. If a new setpoint value is not calculated, this may not be monitored as long as the event has not been triggered. An activity-bit storage location may be introduced which has a first value when the beginning of an event has been triggered, and has a second value when the end of the event has been reached. Based on this activity bit, it may be monitored that no new setpoint values are loaded and calculated during the course of the event. For certain processes in the internal combustion engine, it may be determined, with the aid of the activity bit, how long an event lasts and/or how many cylinders are performing this event simultaneously. In this context, in response to an overly long duration of an event, e.g., a charging of an ignition coil is lasting too long, a disturbance may be recognized and this event may be triggered, i.e., the charging of the ignition coil is ended.